Keep Your PBX. Upgrade Your Lines.
Summit SIP trunks replace your old PSTN lines with VoIP, cutting call costs, adding flexibility and delivering clearer calls over our own network.
- Talk to someone who can fix it, not just log it
- Internet, phones and mobile on one bill
- We tell you what you need, not what we would rather sell
Overview
If your business has invested in an on-premises PBX, you do not need to throw it away to move to VoIP. Summit's SIP trunks connect your existing phone system to our voice network over the internet, replacing expensive PSTN and ISDN lines with flexible, scalable VoIP channels.
The result is lower call costs, the ability to add or remove channels as your business needs change, and access to features like geographic number flexibility and Microsoft Teams integration. And because Summit owns and operates its own network (ACMA Carrier Licence #388), your SIP trunks benefit from genuine Quality of Service prioritisation, not just a best-effort internet connection with fingers crossed.
For businesses that are not ready for a full cloud phone system but want the cost savings and flexibility of VoIP, SIP trunks are the ideal bridge. You keep the PBX you know and trust, and Summit handles the voice connectivity.
Key Benefits
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Lower Call Costs
SIP trunks replace per-line PSTN charges with per-channel VoIP pricing. National calls cost a fraction of traditional line rates, and you only pay for the channels you need. Most businesses see a significant reduction in their monthly telephony spend from the first bill.
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Protect Your Existing Investment
Your on-premises PBX still has years of life left. SIP trunks let you keep that investment while modernising the connection to the outside world. There is no need to retrain staff on a new system or reconfigure your entire call flow. Your PBX continues to work exactly as it does today.
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Scale Channels On Demand
With PSTN lines, adding capacity means ordering new physical lines and waiting for installation. With SIP trunks, adding a channel is a configuration change. Need extra capacity for a busy season? Add channels. Quiet period? Scale back down. You only pay for what you use.
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Crystal-Clear Call Quality on Our Own Network
Generic SIP providers send your voice traffic over the public internet and hope for the best. Summit routes your SIP traffic across our own network with QoS prioritisation, so your calls are clear, consistent and free from the jitter and dropouts that plague lesser providers.
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Geographic Number Flexibility
With SIP trunks, you can present local numbers from any Australian area code, regardless of your physical location. A Melbourne business can present a Sydney number for its NSW clients, or a Brisbane number for Queensland, all routed to the same PBX.
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Microsoft Teams Integration
Summit's SIP trunks can integrate with Microsoft Teams, allowing your team to make and receive external phone calls directly within the Teams interface. Your PBX handles the routing while Teams provides the user experience your staff already know.
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Built-In Redundancy
SIP trunks can be configured with automatic failover to an alternate destination, such as a mobile number, a secondary site, or a cloud-based backup, if your primary connection goes down. Combined with Summit's 4G Backup service, your phones stay operational even during an internet outage.
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One Bill, One Provider
When Summit delivers both your internet connection and your SIP trunks, you get a single bill, a single support team, and a single point of accountability. No more finger-pointing between your internet provider and your voice provider when call quality drops.
How It Works
- 1 Assess your current PBX
Assess your current PBX
Summit reviews your existing phone system to confirm SIP trunk compatibility and determine the optimal configuration. We work with a wide range of PBX vendors and can advise on any firmware updates or settings changes needed.
- 2 Design your SIP trunk configuration
Design your SIP trunk configuration
We determine how many concurrent channels you need based on your call volumes, configure your number presentation (DIDs), and set up any failover rules.
- 3 Provision and test
Provision and test
Summit provisions your SIP trunks on our network, provides the connection credentials for your PBX, and works with you to test inbound and outbound calls before going live.
- 4 Port your numbers
Port your numbers
Your existing phone numbers are ported to Summit's network so your customers, suppliers and marketing materials remain unchanged. Porting is coordinated to avoid any interruption.
- 5 Go live with ongoing support
Go live with ongoing support
Once live, Summit monitors your SIP trunks and provides support from our own team whenever you need it. Adjustments to channel counts, number presentation or routing can be made quickly.
Features
Voice Quality & Network
- QoS Prioritisation
- : Voice traffic prioritised on Summit's own network for consistent call quality
- HD Voice
- : Wideband audio support for compatible handsets and PBX systems
- Jitter Buffer Management
- : Network-level jitter management to smooth call audio
- Redundant Voice Infrastructure
- : Summit's voice platform is hosted across resilient infrastructure with multiple failover paths
Channels & Numbers
- Flexible Channel Counts
- : Start with as few as 2 channels and scale to hundreds as your business grows
- DID Numbers
- : Direct Inward Dialling numbers so callers can reach specific extensions directly
- Geographic Number Presentation
- : Present local numbers from any Australian area code
- Number Porting
- : Bring your existing numbers to Summit at no additional cost
- 1300 and 1800 Compatibility
- : Route inbound 1300 and 1800 numbers through your SIP trunks
Integration & Compatibility
- Broad PBX Compatibility
- : Works with a wide range of on-premises PBX systems from leading vendors
- Microsoft Teams Integration
- : Direct Routing for external calling through the Teams interface
- Fax over SIP (T.38)
- : Fax support for businesses that still require fax capability
- DTMF Support
- : Reliable touch-tone signalling for IVR menus and automated systems
Reliability & Failover
- Automatic Failover
- : Configure alternate routing destinations if the primary connection is unavailable
- 4G Backup Compatibility
- : Pair with Summit's 4G Backup for automatic internet failover, keeping SIP trunks operational
- Dual Registration
- : Register SIP trunks at multiple sites for site-level redundancy
Management & Reporting
- Call Detail Records
- : Detailed records of all inbound and outbound calls for billing reconciliation and analysis
- Usage Reporting
- : Track channel utilisation to right-size your SIP trunk count
- Real-Time Monitoring
- : Visibility into trunk status, registration health and call quality metrics
Use Cases
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The Business with a Working PBX
A 30-person engineering firm has a reliable on-premises PBX that handles their call routing perfectly. But their PSTN lines are expensive and inflexible. SIP trunks replace those lines with VoIP, cutting their monthly call costs while keeping their entire phone system unchanged. The team notices no difference except the lower bill.
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The Multi-Site Organisation
A franchise group with offices in Melbourne, Sydney and Brisbane needs each location to present a local number while routing overflow calls between sites. SIP trunks with geographic DID numbers let each office present its local area code, and inter-site call routing is handled by the PBX over the SIP trunk, at no per-call cost.
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The Microsoft Teams Workplace
Lawyers & AccountantsA professional services firm has standardised on Microsoft Teams for internal communication but needs external calling capability. Rather than replacing their PBX, they use Summit SIP trunks with Teams Direct Routing. Staff make and receive business calls within the Teams app, while the PBX continues to handle advanced routing, queues and IVR in the background.
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The Seasonal Business
An events company handles four times its normal call volume during peak season. With SIP trunks, they scale from 5 channels to 20 for the busy months, then back down again, paying only for what they need, when they need it. No new lines to order, no installation delays, no wasted spend in the quiet months.
Your situation not on this list? Tell us what you run or call 1300 049 749 and we will tell you honestly whether we can help.
Not sure which option is right for your business?
Book a short call with one of our network specialists. Tell them how your business actually runs and they will tell you which access technology suits it, which ones do not, and why. If the cheaper option is the right one, they will say so.
Why Choose Summit for SIP Trunks
- 01
We Own the Network Your Calls Travel On
Most SIP providers are reselling someone else's voice platform over someone else's internet. Summit owns and operates the network (ACMA Carrier Licence #388), which means we control the quality from end to end. When you pair Summit SIP trunks with a Summit internet connection, your voice traffic gets genuine network-level QoS, not a marketing promise.
- 02
Eliminate the Blame Game
When call quality drops, is it the SIP provider or the internet provider? When Summit delivers both, there is no question and no finger-pointing. One team owns the entire voice path and can diagnose and resolve issues without waiting for a third party.
- 03
Melbourne-Based Voice Expertise
Summit's support team is based in Melbourne and understands PBX systems, SIP configuration, and voice networking. When you call with a SIP trunk issue, you speak to someone who can read a SIP trace and configure your trunk, not someone reading from a script.
- 04
Broad PBX Compatibility
Summit's SIP trunks are tested and proven with a wide range of on-premises PBX systems. Whether you are running a system from a major vendor or a lesser-known platform, our team will work with you to ensure compatibility and optimal configuration.
Other services businesses pair this with
Bundle them on one bill →Why Australian Businesses Choose Summit Internet
The Summit Team have always been a pleasure to work with; we highly recommend their services. Thank you for the continued support.
Paul Braithwaite
3 months ago
We recently moved our dental practice over to Summit for phone services, and the experience has been excellent from start to finish. The team has been responsive, professional, and incredibly helpful throughout the entire setup process. The transition was smooth, any issues were addressed promptly, and communication was always clear and efficient. Reliable phones and internet are essential for a busy practice like ours, and Summit has delivered exactly that. A special thank you to Michael for his patience and ongoing assistance during the transition. Highly recommend Summit to any business looking for reliable service and great customer support.Read more
Elli Darabi
3 months ago
The best service !!! Got issue fixed out by Greg ^^
白大倫
3 months ago
The whole team at Summit have been great from the initial onboarding to the rapid responses from Max when we need to make changes or additions to our services. Can't recommend them enough!
Aaron Klaver
3 months ago
As the I.T. Manager for Hydronic Systems Australia, Summit helps provide me and our companies with consistently stable Business Grade Internet, backed up by a dedicated Fixed Wireless Broadband connection. They also saved us a serious amount of money on our mobile phone bills. We have had no serious issues, and our business has been rock-solid under there great service. Highly Recommended.Read more
James Paterson
4 months ago
Prompt and efficient service. Highly recommend
Elliot Bell
4 months ago
We now use Summit across our real estate network. Great family business, reliable and their attention to detail is outstanding. Highly recommend.
Ryan Bell
4 months ago
As a reseller, we primarily work with Summit’s 4G services and have been very impressed. The plans are affordable, flexible, and well suited to our customers—especially for internet failover solutions. The sales and support teams are responsive and genuinely helpful, which is why we’re proud to partner with Summit Internet. We happily recommend them.Read more
Mal Skinner
4 months ago
After working with another ISP for several months to deliver a critical internet service for a major international sporting event, we were ultimately advised that the required upgrade was unlikely to be completed prior to event week. This left us facing a significant risk to service delivery. After exhausting all other options (and a few sleepless nights) we came across Summit Internet. From the initial conversation, Allan immediately understood the severity of the situation and quickly engaged his technical delivery team. Michael “Radar” was on site within days to assess and finalise a solution. Despite challenging conditions, including large trees and other obstructions, he worked tirelessly to design and implement an alternative approach. Leveraging an adjacent building, a temporary NBN connection, and a wireless link into the comms room, the solution was delivered within 24 hours of the initial site visit. Not only was the outcome faster than expected, but it was also more cost effective and delivered higher speeds than originally promised by the previous ISP. Over the course of the event, the service handled terabytes of data and supported hundreds of concurrent users without a single speed or performance issue. I cannot thank Summit Internet, particularly Allan and Radar enough for their exceptional service, technical expertise, and commitment to delivering under pressure. Highly recommended.Read more
Adam Hastie
4 months ago
Fausto and the staff at Summit are amazing. We have had nothing but fantastic service from start up to problem solving issues. The system is easy to use. Would highly recommend this service provider.
Jo Bodhankar
4 months ago
Summit internet recently set my small business up with a local land line number and a soft phone that runs off an app on my mobile - getting my personal phone number off the internet and being able to distinguish between business and personal calls is a game changer. Whole process took less than a week, and is super cost effective. Highly recommend.Read more
Alex Holly
6 months ago
Great service, efficient and smooth from start to finish!
Marija Cavlina
9 months ago
Reviews from Google. Read all reviews on Google
Frequently asked questions
Will SIP trunks work with my existing PBX?
How many channels do I need?
Can I keep my existing phone numbers?
What happens if my internet goes down?
Do SIP trunks support fax?
How do SIP trunks integrate with Microsoft Teams?
What call rates apply?
Is there a minimum contract term?
Ready to Move Your PBX to VoIP?
Get a SIP trunk quote tailored to your PBX, your call volumes and your business. We will make the transition seamless.
Call 1300 049 749 or request a callback · Mon-Fri 9AM-5PM AEST